Published August 09, 2010, 09:03 AM
NWS: Determining the strength of a tornado
Tyler, ND (WDAY TV) - The National Weather Service has rated tornado damage in the southern valley from Saturday's tornado. Near Tyler, North Dakota damage was an EF-3. Across the river near Doran, Minnesota they estimated EF4 damage with winds up to 175 miles per hour. How do they determine the tornado's strength?
